1. Field of the Invention
This invention relates to an electric connection box (i.e., an electric junction box) such for example as a relay box, a fuse box and an electronic control unit box) used in a vehicle such as an automobile, and more particularly to an electric connection box in which a wire harness electrically connected to electrical parts (such as relays, fuses and, electronic control units) is bent in such a manner that a direction of leading of the wire harness out of the electric connection box is regulated to a predetermined direction.
2. Related Art
Electric connection boxes for automobiles are broadly classified into two kinds, that is, the type to be mounted within a passenger compartment and the type to be suitably mounted within an engine room. The electric connection box mounted within the passenger compartment will not basically be exposed to rain and others, and therefore it is not necessary to give much consideration to the waterproofing. In contrast, in the electric connection box mounted within the engine room, a tray-like upper cover and a tray-like lower cover are attached to a connection box body (i.e., a frame-like case) in order not only to achieve the waterproofing but also to prevent dust, dirt and the like from intruding into the engine room.
More specifically, the electric connection box to be mounted within the engine room comprises the connection box body having a plurality of electrical parts mounted thereon, the lower cover attached to a lower portion of the connection box body to cover a bundle of wires (that is, a wire harness) electrically connected to the electrical parts and extending downwardly from the connection box body, and the upper cover attached to an upper portion of the connection box body to cover an upper surface of this connection box body.
Incidentally, within the engine room, a space can be more easily obtained in a direction of a height (that is, a vertical direction) than in a lateral direction (that is, a horizontal direction), and therefore electric connection boxes of the type in which the wire harness is led downwardly out of a lower cover have increasingly be used in automobiles (see, for example, JP-A-2001-211528 Publication).
Among the electric connection boxes in which the wire harness is led downwardly out of the lower cover, there is the type further including a side cover having a plate-like harness holding portion which is fixed to the wire harness by a fixing member such as an adhesive tape and a binding band (see, for example, JP-A-2001-352640 Publication). In the electric connection box having such a side cover, one continuous harness lead-out through hole is formed through a lower wall and a side wall of the lower cover. The wire harness is led out of the lower cover through the harness lead-out through hole, and in this condition the side cover is attached to the lower cover to close an opening of the harness lead-out through hole formed in a side surface (that is, the side wall) of the lower cover. At this time, the wire harness led out of the lower cover is held by the fixing member on the harness holding portion of the side cover which extends downwardly from the vicinity of an opening of the harness lead-out through hole formed in a lower surface (that is, the lower wall) of the lower cover, and therefore the direction of leading-out of the wire harness is regulated to a downward direction relative to the lower cover. In the operation for assembling the electric connection box of this structure, the operation for the leading-out of the wire harness is carried out in the following manner.
First, the connection box body is disposed upside down (that is, the upper surface of the connection box body is directed downward while the lower surface of the connection box body is directed upward) so that the wire harness leading-out operation can be effected easily, and in this condition the wire harness extending from the lower surface of the connection box body is passed through the harness lead-out through hole in the lower cover. Then, the lower cover is attached to the connection box body while engaging engagement portions of the lower cover with respective retaining portions of the connection box body. At this time, most of wires of the wire harness are bent generally at a right angle partly because an inner surface (particularly an upper surface of the lower wall of the lower cover facing away from the lower surface thereof) of the lower cover is pressed against these wires, and the wires extend along the inner surface of the lower cover, and are led out through the harness lead-out through hole (When the wire harness is thick, and can not be easily bent, the wires are led to the exterior mainly through the opening of the harness lead-out through hole formed in the side surface of the lower cover.). Then, the harness holding portion of the side cover is fixed by the fixing member (such as an adhesive tape and a binding band) to a predetermined portion of the wire harness led out of the lower cover. Then, that portion of the wire harness spaced slightly from the fixing member toward the connection box body is bent generally at a right angle so that the wire harness extends upwardly from the opening of the harness lead-out through hole formed in the lower surface of the lower cover (That portion of the wire harness led out of the lower cover extends downwardly when this electric connection box is actually mounted on the vehicle.), and in this condition engagement portions of the side cover are engaged respectively with retaining portions of the lower cover to thereby attach the side cover to the side surface of the lower cover,.
In such an electric connection box, particularly when the wire harness is so thick as not to be easily bent, the worker must engage the engagement portions of the lower cover with the respective retaining portions of the connection box body with a larger force against the spring back of the wire harness (that is, an elastic restoring force of the wire harness), that is, in a manner to forcibly press the side cover, and this engaging operation can not be carried out easily, and therefore the efficiency of the assembling operation is low. And besides, when attaching the side cover to the lower cover in the condition in which the harness holding portion of the side cover is fixed to the wire harness, the wire harness must sometimes be forcibly twisted, and therefore an improvement is necessary in view of the efficiency of the assembling operation. Furthermore, the wire harness need to have a surplus portion for bringing the engagement portions of the side cover into engagement with the respective retaining portions of the lower cover, and this is a waste of resources.